FM 5-20A War Department Field Manual, Corps of Engineers, Camouflage of Individuals and Infantry Weapons 1944-02-09
"Parts of this FM include helmet camouflage, skin tonedown, canvas equipment, blending with one's background, shadows, movement, foxholes, machine guns, mortars, antitank guns, etc."
Digitized by the Combined Arms Research Library (CARL) Digital Library, US Army Combined Arms Center. http://cgsc.cdmhost.com/cdm/
Manuals in the FM 5-20 series : FM 5-20, FM 5-20A, FM 5-20B, FM 5-20C, FM 5-20D, FM 5-20E, FM 5-20F, FM 5-20G and FM 5-20H